How are squid tentacles different from squid arms?

While the terms are sometimes used interchangeably, there are distinct anatomical differences between the arms and tentacles of a squid.

Squids possess a total of ten appendages: eight are classified as arms, and two are classified as tentacles. The primary differences include:12

• Sucker Distribution: Arms are characterized by having suckers along the majority of their length. In contrast, tentacles typically feature suckers only at their expanded ends.213
• Structure and Function: Arms are generally shorter and more compact, while tentacles are long and slender. In many species, these tentacles are specialized for capturing prey.132
• Specialized Features: Depending on the species, these appendages may also feature different armaments. For example, while some squids have suckers with toothed, horny rings on their tentacles, others—such as the colossal squid—possess rotating hooks framed by tiny suckers on their tentacular clubs.14

These appendages are key features used by scientists to distinguish between various cephalopod species.5